Low frequency electric and magnetic fields are produced as a consequence of alternating current (AC) power distribution. AC power produces forward and reverse currents at a rate of 60 times per second (60 Hertz). The alternating current results in expanding and contracting electric and magnetic fields at a 60 Hertz (Hz) rate.
Recent studies have indicated that 60 Hz electric and magnetic fields may be associated with childhood cancer. In particular, in two recent studies, an association between childhood cancer and proximity to 60 Hz power distribution equipment has been suggested. However, other studies have indicated no significant relationship between childhood cancer and 60 Hz electric and magnetic fields.
In addition to proximity to 60 Hz power distribution equipment, concern has been raised about the particular health risks posed by electric blankets and mattress pads. Although all electric appliances have associated electric and magnetic fields, electric blankets and mattress pad products are different because of their prolonged use in close proximity with the body.
For example, a toaster or hair dryer is used for several minutes, and at a distance of several feet from the body. On the other hand, an electric blanket or mattress pad is used for seven or eight hours and is generally in close contact with a large portion of the body. One recent study estimated that the typical use of an electric blanket or mattress pad nearly doubles a person's magnetic field exposure and increases the electric field exposure by about one third.
In view of the uncertainty regarding the health risks associated with 60 Hz electric and magnetic fields, medical experts have recommended that children and pregnant women avoid electric blankets and mattress pads altogether.